Some things that I haven't learned yet

[Soakedlontra]

I know you have Bob's handout, which is worth going through carefully again, if you are still confused.

But gas management at the simple recreational dive level basically breaks down into three steps.

First, determine your "rock bottom" or minimum gas. That's the reserve you need to carry to get you and your buddy to the surface from the deepest part of the dive. A reasonable rule of thumb is 20 cu ft for 60 fsw, and 40 from 100fsw. Knowing the volume, you can figure what proportion of your tank it is -- for example, 40 cu ft is half of an Al80 which is normally filled to 3000 psi, so it's 1500 psi. If you know the tank factor for your tank, you can figure it that way.

So -- you take out the rock bottom, and figure out how much gas you have left. That's your "usable" gas.

Now you have to decide how you are going to portion out that gas. If you are diving off a charter boat that will come and get you wherever you end up, you can use it all! Your rock bottom is plenty to get you to the surface, even if you have to share with a buddy. So you head up when you hit rock bottom.

If you are shore diving, most of the time, you would prefer to get back to where you started underwater, rather than do a long surface swim. But you CAN do the long surface swim if you have to. So you divide your usable gas in half. Whatever number you come up with, you add that to your rock bottom, and that's your turn pressure (you turned when you had enough gas to get back to the shore, and to ascend if you needed to).

If you are in a position where you MUST get back to your starting point, then you have to consider that you might have to bring your buddy back there on your gas, AND do the ascent on your gas, so you have to divide that usable gas into thirds. There aren't many situations where open water divers are faced with these constraints, but diving wrecks in high current off an anchored boat is one of them.

Don't make it too complicated in your head. It's really simple. Put away a safety reserve that you won't use. Then decide whether the dive is one way, two way, or "absolutely have to get back to the upline". That tells you how to divide the rest.

Quick examples:

Diving off a Bandito charter at Sunrise. Max expected depth is 60 fsw. You're diving an LP95, with a tank factor of 3.5 (rounded off for easy math). You need a safety reserve of 20 cu ft, which is roughly 600 psi (6 x 3.5 = 21). So you put 600 psi away. The boat will come and get you wherever you surface, so you can use your tank down to 600 psi, so you have 2000 psi usable (assuming you got the 2640 fill the tank is rated to). You have no turn pressure. You ascend at 600 psi, or when you get cold, whichever comes first.

Diving at Edmonds. Max expected depth is probably 33 fsw, and rock bottom is never less than 500 psi, so that's what it will be for this dive. This is a halves dive, because you'd really LIKE to swim back to the shore, although if you have to surface, you can. So you take that 2640 you have, remove the 500 psi reserve, and that gives you 2140 -- rounding down to 2000, you have 1000 to use going out, and 1000 to use coming back. So add the 1000 you need to come back to the 500 you aren't going to touch outside of an emergency, and you have a turn pressure of 1500 psi.

Diving off the Dash on the Possession Point ferry. Max depth is 80 fsw, and the boat is anchored, and surface currents can be fierce. So if you have a problem at depth, you would like to share gas to the upline and ascend there if you possibly can. So, using the 100 fsw value of 40 cu ft, you need to set aside 900 psi for rock bottom. That leaves you with 1700 psi usable. Now you want to divide that into thirds, and you have to make a decision. 1700 isn't divisible by 3, so you either have to call it 1500 or 1800 to make the math easy. 1800 reduces your safety cushion; 1500 is very conservative. What you do may depend on how much you trust your buddy, how much experience you have, or how worried you are about drifting in the open water until the boat finds you Say we want to be conservative and careful -- we'd call our outbound leg 500 psi, and turn at 2100.

The math is easy, once you decide how you are going to apportion the gas.

Thank you for your long detailed reply. I will have to read it several times as well as Bob's notes without, as you mentioned, trapping my brain in a maze of numbers.

Cheers

 

[Soakedlontra]

Hi Offthewall1,

I cannot wait to get a wrist/hand mount light but for now I have to manage with the one that I have. Now it hangs vertically down when I keep it hooked up on a D ring instead of an angle. Does it make a difference? Ma!

I checked my weight during my AOW class and it turned out that I was a bit light.

At last I don't forget pieces of gear as often as I used to anymore. I still look at a list for the time being.

Breathing: I don't think that it is too bad, but I could try to breathe deeper and see what happens.
I suspect that one of the reasons why I use so much air is feeling cold. I have made the first step to solve this problem by buying a used dry suit (could not afford a new one) and gradually I will make the transition from diving semi-dry to dry.

Cheers

 

[offthewall1]

Hi Offthewall1,

I cannot wait to get a wrist/hand mount light but for now I have to manage with the one that I have. Now it hangs vertically down when I keep it hooked up on a D ring instead of an angle. Does it make a difference? Ma!

I checked my weight during my AOW class and it turned out that I was a bit light.

At last I don't forget pieces of gear as often as I used to anymore. I still look at a list for the time being.

Breathing: I don't think that it is too bad, but I could try to breathe deeper and see what happens.
I suspect that one of the reasons why I use so much air is feeling cold. I have made the first step to solve this problem by buying a used dry suit (could not afford a new one) and gradually I will make the transition from diving semi-dry to dry.

Cheers

Glad to hear things are getting better... keep plugging away at it... and best of luck!

 

[TSandM]

The issue of what to do with buddies is a sticky one.

I believe it is good to dive with different people, because if you only dive with one buddy, the two of you begin to develop a dynamic that tends to divide the dive responsibilities so that each person does what he's good at. In that situation, nobody builds capacity in the areas where they are weak. So it's good to dive with different folks, and take different roles in the dive, to become facile with all responsibilities.

BUT -- Especially as a new diver, I think you have to be selective, and you have to have a pre-dive discussion that includes what your expectations and needs from your buddy are. There are wildly divergent philosophies of diving, ranging from the unified team concept I espouse to people who get in the water together but don't expect to dive together or even end the dive together. What is important is that the people who are in the same buddy group have the SAME expectation of one another, and how the dive will go. Anything else leads to stress and discomfort on the part of at least one buddy. I do not believe there is any benefit to diving with someone whose expectations of the dive are so discordant from yours that you are doomed to be unhappy and stressed (which is why I didn't dive with my husband for the first six months!)

It is okay to be new, and it is okay to ask your buddy to respect certain parameters or limitations, and if your buddy-to-be is not content with those limits, you should probably both find other people with whom to dive.

 

[Soakedlontra]

I write notes that sometimes look like essays in my log book as soon as possible after each dive, because you are right I have noticed that if I let too much time go by the memories about the dives get blurred and more inaccurate. Something that hardly other divers do nowadays ( some even look at a paper log book almost with contempt!).

I have also need to take some time to 'analyze' the data that I collect after each dive to figure out my own general trend in gas consumption and how it fluctuates with depth and dive profile (Do I make sense?) without getting too caught with numbers.

Another issue that has been cropping up lately is how to deal with what I would call "solo-divers-by-default" (they go solo when they cannot find a buddy). In the case of the guy that I mentioned in my previous post, I did make a conscious effort to keep myself calm and relaxed (while my instinct kept ringing alarm bells.

On a gut level I feel that those kind of divers have a potential to become trouble, but on the other hand I think that I need to learn how to cope with divers that have different 'styles' of diving from mine, but then where do I draw the line? (In this particular case he turned out to be ok).

That diver never dived from a boat before and it came natural to me to tell him to remember to inflate his wing before jumping in the water (it was also a reminder for myself), He then remarked: " So are you not going to rescue me if something happens?" and I replied "I would rather avoid to put myself in that situation if I can help it" (something like that I don't remember the exact words) then a deep silence followed...Jeeezzz and I felt terrible....

I do believe that it is better to be honest that pretending to be a 'hero' when I know perfectly well that I do not know how I would respond to an emergency without any training and my lack of experience of dealing with emergencies in general (never being involved in car accidents etc, let's touch wood and ferro) and my vague belief that I may end up getting overwhelmed by panic and be totally useless. For now prevention is the only concrete thing that I can hang on to it with some knowledge.

This is really a sticky issue especially when diving with people whom I do not know at all. I don't even know whether it is appropriate to bring it up in the first place or not. Who wants to stir up this gloom and doom at the beginning of a dive?
(For obvious reasons I don't have a problem in discussing this uncomfortable subject with my regular buddy and other divers who I know and are more experienced than me).

Good Lord! This post doesn't make much sense... Too much scubadiving I guess...

I am too tired to edit it...so voila'...buona notte!

 

[Soakedlontra]

The issue of what to do with buddies is a sticky one.

I believe it is good to dive with different people, because if you only dive with one buddy, the two of you begin to develop a dynamic that tends to divide the dive responsibilities so that each person does what he's good at. In that situation, nobody builds capacity in the areas where they are weak. So it's good to dive with different folks, and take different roles in the dive, to become facile with all responsibilities.

BUT -- Especially as a new diver, I think you have to be selective, and you have to have a pre-dive discussion that includes what your expectations and needs from your buddy are. There are wildly divergent philosophies of diving, ranging from the unified team concept I espouse to people who get in the water together but don't expect to dive together or even end the dive together. What is important is that the people who are in the same buddy group have the SAME expectation of one another, and how the dive will go. Anything else leads to stress and discomfort on the part of at least one buddy. I do not believe there is any benefit to diving with someone whose expectations of the dive are so discordant from yours that you are doomed to be unhappy and stressed (which is why I didn't dive with my husband for the first six months!)

It is okay to be new, and it is okay to ask your buddy to respect certain parameters or limitations, and if your buddy-to-be is not content with those limits, you should probably both find other people with whom to dive.

In the case of the boat dive I did not have a choice, though. What troubled me at first was the fact that he would go solo when he could not find a buddy.

A while ago I had an experience with a similar diver who was pretty much self-absorbed and a little bit too busy taking pictures at Cove 2. He also had the scuba-myth-belief that women use less air than men. I ended up chasing him around getting a bit stressed (later on I realized it was a waste of gas).

When I was at 500 PSI I signaled him several times that I was getting low on air. Eventually he finally and reluctantly came up to the surface. He then told me that he wanted to keep diving on his own to use up his 800 PSI. In our pre-dive discussion we did not discuss this scenario. I was totally taken by surprise by his behavior that I did not know what to say. At the end we separated and I swam back to the beach by myself while he went back down in about 20 feet of water (God bless him!)

I did not bring up this particular issue that I had with the Cove 2 diver with the diver on the boat because I simply forgot as I forgot to discuss what we would do if we got separated (he did not bring it up either)

The boat diver is taking technical diving classes and when I asked him to do a bubble check he did not know what I was talking about. I insisted to do this check at the beginning of every freaken dives and we did.

Why did I have to work so hard to make those two buddies to listen?

Either you are a solo diver and dive with similar people if you want some companionship but you don't want to make any concessions whatsoever about your dive style or if you decide to have a buddy then you should take also the responsibility to be less selfish and be able to adapt and have fun at the same time rather than perceiving your buddy as a pain in the neck and hassle. Unfortunately there are a lot of divers out there who prefer deception from honesty and don't simply care if they become a potential hazard to their buddies.

I agree with you, it is an invaluable learning experience to dive with different people within certain limits, though.

During the pre-dive-discussion I have noticed that some people have the tendency to take short cuts and when it comes to talk about emergencies...well they roll their eyes assuming that it would never happen with them. I have to insist to talk about it with the risk to turn myself into a pedantic, boring fart!

At the same time it is a bit disconcerting to notice that I have been forgetting to discuss certain aspects of the dive just because of my bad memory or because I am learning to skip things as well?

Maybe I should start writing another list...

 

[sambolino44]

Well, I haven't had very many new buddies lately, but even with some of my somewhat-normal buddies I forget things to discuss before the dive, so I think I'm going to make a "New Buddy Pre-Dive Brief Checklist". Come to think of it, it might not be a bad idea to make a "Same-Old Usual Buddy Pre-Dive Brief Checklist" because we sometimes forget to nail down any contingencies before we hit the water.

 

[elan]

If I start posting what I still have to learn the moderators will probably shutdown my account for spamming

 

[cowdog77]

I use my well-worn but still readable laminated "boat dive list" that I keep in an outside pocket of my boat bag. It lists in priority order only the items I'll take on a boat dive, and has kept me from sitting out a dive several times.

 

[TSandM]

One of the things I really like about the standardized system in which I dive, is that the pre-dive checklists are simple, and everybody knows what they are. So if I forget a step, someone else will call me on it.

The flip side is that, when I dive with people who don't use the system, I forget stuff like checking weights or releases or how their inflator works.

One of the things I have learned from reading SB for almost four years, is that hooking up with instabuddies is an enormous source of frustration and uncomfortable (to dangerous) experiences for a lot of people. For me, not so much, because when I dive with new divers (which are my only instabuddies) we follow my checklists and pre-dive procedures. My "instabuddies" are people who dive the same way I do, and it always feels like diving with old friends. Standardization has some very powerful arguments in its favor.